On Wed, 14 Feb 2007, Ingo Molnar wrote: > > * Evgeniy Polyakov <[EMAIL PROTECTED]> wrote: > > > Let me clarify what I meant. There is only limited number of threads, > > which are supposed to execute blocking context, so when all they are > > used, main one will block too - I asked about possibility to reuse the > > same thread to execute queue of requests attached to it, each request > > can block, but if blocking issue is removed, it would be possible to > > return. > > ah, ok, i understand your point. This is not quite possible: the > cachemisses are driven from schedule(), which can be arbitraily deep > inside arbitrary system calls. It can be in a mutex_lock() deep inside a > driver. It can be due to a alloc_pages() call done by a kmalloc() call > done from within ext3, which was called from the loopback block driver, > which was called from XFS, which was called from a VFS syscall. > > Even if it were possible to backtrack i'm quite sure we dont want to do > this, for three main reasons:
IMO it'd be quite simple. We detect the service-thread full condition, *before* entering exec_atom and we queue the atom in an async_head request list. Yes, there is the chance that from the test time in sys_async_exec, to the time we'll end up entering exec_atom and down to schedule, one of the threads would become free, but IMO better that blocking sys_async_exec. - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
